Method and device for reconstructing existing bridges and highways with minimal disruption of traffic

ABSTRACT

A method of erecting a new elevated roadway ( 41 ) above an existing roadway ( 21 ) in order to increase traffic capacity and restore structural integrity of bridge roadway ( 23 ) with minimal disruption of traffic. Roadway ( 41 ), which comprises a plurality of interconnected ramp units and bridging units, is erected in multiple steps by initially erecting entrance/exit ramp units ( 43 ) and ( 45 ) with their uppermost ends facing each other. Then intermittently, during periods of off-peak traffic, creating a gap in a previously erected portion of roadway ( 41 ) by moving ramp unit ( 45 ) along roadway ( 21 ), erecting a bridging unit in the gap, and opening an extended portion of roadway ( 41 ) to traffic during periods of peak traffic. Structural integrity of roadway ( 23 ) is then restored by repeatedly closing a number of existing travel lanes to traffic, while rerouting traffic onto the newly erected roadway (41), and restoring structural integrity of the closed travel lanes without interruption. This method can be used for reconstructing different types of bridges and highways.

BACKGROUND

[0001] 1. Field of Invention

[0002] This invention relates to the field of reconstructing existing bridges and highways, specifically to methods and devices used to increase traffic capacity and to restore structural integrity of existing roadways.

[0003] 2. Prior Art

[0004] There are more and more vehicles that use existing transportation infrastructure. Due to a drastic increase in traffic load and volume, this aging infrastructure is rapidly deteriorating and traffic capacity of existing roadways is becoming inadequate. At the same time, especially in urban areas, constructing new transportation facilities is severely restricted by environmental regulations, high costs, and existing land development. Therefore, reconstructing existing bridges and highways in order to increase their traffic capacity and restore their structural integrity remains very often the only choice available.

[0005] Prior art practices considered increasing traffic capacity and restoring structural integrity of existing roadways as two unrelated problems, not recognizing that they are actually interdependent. Consequently, two distinct groups of prior art methods have been developed: one that concentrates on increasing traffic capacity of existing roadways, and the other that concentrates on restoring their structural integrity. This lead to incomplete prior art solutions, as is evidenced by the persistent inferior conditions of transportation infrastructure today.

[0006] Prior art methods of reconstructing existing roadways in order to increase their traffic capacity include either widening existing roadways, or erecting new elevated roadways above existing roadways. In urban areas, erecting new elevated roadways is used most frequently, because widening existing roadways is often constrained by right-of-way restrictions and environmental considerations. Various methods and devices have been proposed for erecting elevated roadways above existing roadways, as described in U.S. Pat. No. 2,225,186 to N. C. Sorensen (1940), U.S. Pat. No. 3,211,110 to R. M. Pierson (1965), U.S. Pat. No. 3,301,146 to S. Krug et al (1967), U.S. Pat. No. 3,406,616 to E. McLean (1968), U.S. Pat. No. 5,846,020 to K. McKeown (1998), U.S. Pat. No. 5,960,502 to Y. Sherman et al (1999), and European Patent 424223 to C. Defontaines (1991).

[0007] According to the prior art, elevated roadways are usually erected of various types of frames supporting a structural floor system and a roadway deck, or of reinforced concrete box units. Reinforced concrete systems are very heavy, and that practically precludes their use on existing bridges, which are not commonly designed to support a substantial additional load. In addition, curing of field poured concrete joints during erection of the concrete units requires significant time, which leads to interruption of existing traffic. Structural steel systems of the prior art provide very few additional travel lanes, some even provide single lanes, channeling traffic. The latter is not acceptable as a permanent roadway at all, due to a possibility of car or truck breakdowns.

[0008] Furthermore, erecting a new elevated roadway above an existing one using these prior art methods and devices requires at least a partial closure of the existing roadway for extended periods of time during erection, causing severe disruption of existing traffic. Even if traffic were detoured from the existing roadway undergoing reconstruction, traffic would spill over onto adjacent roadways, creating traffic jams and safety hazards there and resulting in increased air pollution, costly disruption of local businesses, and interference with local traffic.

[0009] Transportation authorities, such as Federal, State, and Municipal Departments of Transportation, public and private transportation agencies, that govern existing bridges and highways, recognize the problem of traffic disruption that occurs during restoration of existing roadways. And since traffic volumes on existing roadways vary significantly between peak and off-peak traffic, the authorities issue regulations that specify when and how many of existing travel lanes shall be open to traffic, and when and how many of them may be closed with minimal disruption of existing traffic. Generally, all travel lanes of existing roadways are required to be open during periods of peak traffic, from early morning to late afternoon, but a predetermined number of the lanes are specified to be closed during periods of off-peak traffic, generally during night hours, with minimal disruption of existing traffic.

[0010] The aforementioned regulations provide window of opportunity for development of a method of erecting a new elevated roadway above an existing roadway with minimal disruption of traffic that prior art methods have not successfully utilized. And as a result, many existing bridges and highways, especially in urban areas, suffer from insufficient traffic capacity and remain functionally deficient for decades.

[0011] There are several prior art methods of reconstructing existing roadways in order to restore their structural integrity. One of the methods involves closing an existing roadway to traffic while detouring traffic onto alternative roadways. However, detours are not always possible and, when they are, they are costly, create traffic jams and safety hazards on adjacent roadways, and increase air pollution.

[0012] Another method involves closure of at least one of the existing roadway's travel lanes to traffic for a duration of its restoration, while traffic is diverted onto those travel lanes that remain open. When restoration of the closed lane is completed, and the lane is reopened to traffic, the same procedure is then repeated for other travel lanes, resulting in restoration of the entire roadway. This method, however, is infrequently used because the existing travel lanes that remain open to traffic need to accommodate traffic from the closed lane. This can only take place on an existing roadway that has an overabundance of traffic capacity, which is a rare occurrence, especially in urban areas.

[0013] Still other methods utilize slowly advancing moveable elevated roadways, that provide a travel path for existing traffic, while restoration work is performed underneath. They are described in U.S. Pat. No. 1,924,779 to B. H. Flynn (1933), U.S. Pat. No. 3,811,147 to R. C. Dix (1974), U.S. Pat. No. 4,698,866 to H. Kano (1987), U.S. Pat. No. 5,042,957 to M. Arita et al (1991), U.S. Pat. No. 5,105,494 to D. C. Ogg (1992), German Patents DE2653515 to G. Albersinger (1978), DE3107408 to H. R. Baser (1982), and British Patent GB2227268 to H. R. Fish (1990). Some of these moveable roadways provide an overpass with a single travel lane only. They are designed for easier transport from site to site, however, in order to restore an entire width of an existing roadway, these moveable roadways have to make several passes over the same portion of the existing roadway. Other moveable roadways cover an entire width of an existing roadway, which can be restored in a single pass. But they are very expensive to transport from site to site and require significant assembly and disassembly, which disrupts existing traffic. Also, due to significant additional weight that these devices impose on an underlying existing structure, their use on bridges is extremely limited.

[0014] If none of the previously described prior art methods can be utilized, which is currently the case on most existing bridges and highways, then a travel lane is closed to traffic for a relatively short duration of time, usually during night hours, as specified by the transportation authority, and construction equipment and materials are brought to a roadway restoration area prior to start of restoration work. A relatively small area of the closed lane is then restored overnight, in sub-standard conditions and in a rushed manner. Construction equipment and materials are then removed from the restoration area prior to re-opening the previously closed travel lane for peak traffic, usually by early morning. As a result, the restoration work sometimes takes years to complete, an useful life of the roadway restored in such an intermittent way is usually much shorter and a cost of the restoration is much higher than that achieved by using uninterrupted restoration methods.

[0015] The previous discussion, thereby, provides a basis for recognizing that an underlying and mostly not apparent problem of inadequate traffic capacity of existing roadways is the major reason why inferior methods of roadway restoration are presently used. While tens of billions of dollars are spent every year on restoration of transportation infrastructure, existing bridges and highways continuously remain in need of repair.

SUMMARY

[0016] In accordance with the present invention a new elevated roadway, which comprises a plurality of interconnected ramp units and bridging units, is erected above an existing roadway with minimal disruption of existing traffic. This new elevated roadway increases traffic capacity of the existing roadway by providing elevated travel lanes. These elevated travel lanes can then be used to divert existing traffic from the existing roadway, thus enabling restoration of structural integrity of the existing roadway to be performed continuously, with minimal disruption of existing traffic. This method is easily adapted for use on different types of bridges and highways. It is especially valuable in conjunction with car and truck traffic separation, which provides reduction in design live load and thus compensates for an additional weight of the new elevated roadway.

[0017] Objects and Advantages

[0018] The primary object of the present invention is to provide a novel, relatively simple and economical solution to the two most frequently encountered problems in the field of reconstruction of existing bridges and highways, which are increasing traffic capacity of existing roadways and restoring their structural integrity, both with minimal disruption of existing traffic. This primary object is accomplished by developing interrelated methods and devices that, working synergistically, provide a thorough fulfillment of both tasks.

[0019] Accordingly, a highly efficient method of erecting a new elevated roadway above an existing roadway with minimal disruption of traffic is provided. In accordance with the preferred embodiment of this method, the new elevated roadway, comprising a plurality of interconnected ramp units and bridging units, is erected in multiple steps, mostly during periods of off-peak traffic, and it is opened to existing traffic after completion of each step to meet peak traffic demand.

[0020] The initial step of erecting a new elevated roadway involves erecting at least two entrance/exit ramp units, at least one of which is made moveable. The ramp units are positioned so that an uppermost end of one unit faces an uppermost end of another ramp unit and, when erection of the ramp units is completed, they embody an initial portion of the new elevated roadway that may be opened to traffic, if specified by the transportation authority.

[0021] The next step, which is executed during a period of off-peak traffic, involves closing the initially erected portion of the elevated roadway to existing traffic, as specified by the transportation authority, creating a gap in the previously erected initial portion of the elevated roadway by moving the moveable ramp unit along the existing roadway. A bridging unit is then erected in the gap and the moveable ramp is moved back, if necessary, to adjoin the bridging unit. Consequently, an extended portion of the elevated roadway is erected, and it is opened to existing traffic, as specified by the transportation authority to meet peak traffic demand.

[0022] The step of closing a previously erected portion of the elevated roadway to existing traffic during a period of off-peak traffic, as specified by the transportation authority, creating a gap in the previously erected portion of the elevated roadway by moving the moveable ramp unit along the existing roadway, erecting a bridging unit in the gap, and opening an extended portion of the elevated roadway to existing traffic, as specified by the transportation authority to meet peak traffic demand, is repeated many times until erection of the new elevated roadway is completed.

[0023] Thus, by utilizing the novel method of the present invention, the new elevated roadway is erected with minimal disruption of existing traffic, because, at each step, the elevated roadway is open to existing traffic during periods of peak traffic, and a portion the elevated roadway is closed to existing traffic only during periods of off-peak traffic.

[0024] According to the primary object of this invention, a reliable and efficient method of restoring structural integrity of existing roadways with minimal disruption of traffic is also provided. This novel method of restoring structural integrity of existing roadways comprises the following steps:

[0025] (A) first erecting a new elevated roadway above an existing roadway with minimal disruption of existing traffic, using the novel method of erecting a new elevated roadway as presented above, whereby increasing traffic capacity of the existing roadway,

[0026] (B) then restoring structural integrity of a predetermined portion of the existing roadway by repeatedly, until structural integrity of the predetermined portion of the existing roadway is restored, closing at least one of the existing travel lanes to existing traffic while rerouting traffic onto the elevated roadway, restoring structural integrity of the travel lanes closed to traffic, and opening the restored travel lanes to existing traffic, whereby restoring structural integrity of the existing roadway with minimal disruption of existing traffic.

[0027] Another major object of the present invention is to provide an effective structural form of main frames of ramp units and bridging units that enable erecting new elevated roadways with minimal disruption of traffic and faster than when prior art structural forms are utilized. The main frames, usually of T, double-T (TT), or portal types, are generally oriented transversely to the direction of traffic and provide support to secondary structural members, like stringers, cross-beams, and roadway decks. The main frames and other structural members may be made of steel, aluminum, other light-weight alloys, or fiber reinforced composite materials in order to minimize their weight, which is especially important when elevated roadways are erected over existing bridges.

[0028] The main frames are positioned over existing load-carrying structural members of the underlying existing roadway. These load-carrying members are usually located beneath a surface of the existing roadway, and their condition remains unknown until erection work begins, and a portion of a roadway deck is removed. Therefore, when a new elevated roadway is erected over an existing roadway and the main frames are connected to the load-carrying members of the existing roadway, the work is time-consuming and complex, especially if performed at night, because it requires proper surveying and field adjustments based on the existing conditions of the underlying members.

[0029] In order to expedite erecting of main frames by performing the most time consuming and complex work during daytime, a main frame of the present invention comprises at least one base assembly, at least one elevated assembly, and at least one splice assembly. A lower end of the base assembly is supported beneath the existing roadway by the load-carrying structural members of the existing roadway, and an upper end of the base assembly is located above the existing roadway. A lower end of the elevated assembly is supported by the upper end of the base assembly and is connected to the base assembly by the splice assembly above the existing roadway.

[0030] Although additional splices are usually not encouraged because they add materials, labor, time and cost, providing the main frames with field splices, located above the surface of the existing roadway, in conjunction with the novel method of erecting new elevated roadways results in unexpected benefits and advantages of saving time of erecting and increasing quality of workmanship. Due to this novel feature, the work of installing the base assemblies and connecting them to the existing load-carrying structural members is performed under the moveable ramp unit, usually during daytime, since it does not interfere with existing peak traffic. Therefore, this work is performed with minimal time pressure and greater safety, the conditions of the existing load-carrying members can be properly surveyed, and connections may be adjusted as necessary.

[0031] When the elevated assemblies are then connected at night to the previously installed base assemblies, the work is no longer that complex, because it only involves splicing new parts, which may be pre-matched during fabrication. Therefore, this novel feature provides a synergistic effect by converting complex night-time work, involving connecting to the existing members of unknown condition, into much more simple work of splicing new structural members.

[0032] Another object of this invention is to make it versatile enough to be used on different types of existing bridges and highways. This object is achieved by minimizing additional dead load applied to the existing roadway by making the new elevated roadway of relatively light-weight materials, by restricting elevated roadway traffic to “passenger cars only” traffic, and by reducing existing live load by restricting truck traffic to a minimal number of existing travel lanes, as specified by the transportation authority. Since a live load imposed by truck traffic is several times higher than a live load imposed by “passenger cars only” traffic, it is possible to erect the new elevated roadway carrying several “passenger cars only” travel lanes, without overloading the existing roadway. This object is further achieved by utilizing different types of main frames, since vertical members of the frames provide a natural line of separation of truck and “passenger cars only” traffic.

[0033] Another object of this invention is to reduce time required for reconstructing existing roadways. During erection of a new elevated roadway, this object is achieved by utilizing space beneath a moveable ramp unit to install base assemblies of main frames during daytime hours, while peak traffic uses the elevated roadway overhead. Together with the rest of the work performed during off-peak traffic hours, erecting is conducted continuously around the clock. In addition, a space beneath the new elevated roadway is utilized to store construction and safety equipment and materials, and to house a construction field office and a staging area, thereby saving time usually required to bring these items and personnel to and from the work area. During restoration of structural integrity of an existing roadway, this object is achieved by closing travel lanes to existing traffic for the duration of their restoration, so that the restoration work may be conducted around the clock as well.

[0034] Another object of this invention is to achieve a higher level of safety for workers and motorists during reconstruction of an existing roadway, as well as for motorists after the reconstruction is completed. This object is achieved by adding a sufficient number of new travel lanes, therefore reducing congestion and upgrading the level-of-service. A higher level of safety is also achieved by allowing “passenger cars only” traffic on a new elevated roadway, thus separating car and truck traffic. Safety is also improved because construction equipment, barriers and personnel need not to be moved often to and from a work area, and the workers beneath a elevated roadway are protected from traffic by construction traffic barriers. Furthermore, a separate travel lane designated for emergency vehicles only may be integrated as a safety feature as well. Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the following examples and accompanying drawings.

DRAWINGS

[0035] Drawing Figures

[0036] In the drawings, closely related figures have the same number but different alphabetic suffixes. Likewise, closely related reference numerals have the same number but different alphabetic suffixes.

[0037] Also in the drawings:

[0038] North direction shown thus:

[0039] direction of traffic on existing roadway shown thus:

[0040] direction of traffic on new elevated roadway shown thus:

[0041] direction of movement of moveable ramp unit shown thus:

[0042] travel lane marking lines shown thus: - - -

[0043] roadway traffic barriers shown thus:

[0044] construction traffic barriers shown thus:

[0045] bridge roadway restoration area shown thus:

[0046]FIG. 1 (PRIOR ART) shows a perspective view of an existing roadway that is being reconstructed utilizing prior art methods.

[0047]FIGS. 2A and 2B show perspective views of the existing roadway during an initial step of erecting a new elevated roadway.

[0048]FIGS. 3A and 3B show perspective views of the existing roadway during a subsequent step of erecting the new elevated roadway.

[0049]FIGS. 4A and 4B show perspective views of the existing roadway during an intermediate step of erecting the new elevated roadway.

[0050]FIGS. 5A and 5B show perspective views of the existing roadway during the final step of erecting the new elevated roadway.

[0051]FIGS. 6A and 6B show a perspective view and a cross-sectional view, respectively, of the existing roadway and new elevated roadway during an initial step of restoring structural integrity of an existing bridge roadway.

[0052]FIGS. 7A and 7B show a perspective view and a cross-sectional view, respectively, of the existing roadway and new elevated roadway during the final step of restoring structural integrity of the existing bridge roadway.

[0053]FIG. 8A and 8B show a perspective view and a cross-sectional view, respectively, of the existing roadway and the new elevated roadway after erection of the new elevated roadway and restoration of the existing bridge roadway have been completed.

[0054]FIGS. 8C and 8D show cross-sectional views of the existing roadway and alternative new elevated roadway using double-T-type and T-type main frames, respectively, after erection of the new elevated roadway and restoration of the existing bridge roadway have been completed.

[0055]FIGS. 9A and 9B show perspective views of the existing roadway, new elevated roadway, and a local road during two consecutive sub-steps, respectively, of erecting a bridging unit of a new additional elevated roadway.

[0056]FIGS. 10A, 10B and 10C show detailed perspective views of the existing roadway during three consecutive sub-steps, respectively, of erecting a bridging unit of the new elevated roadway.

[0057]FIG. 10D shows a detailed cross-sectional view of the existing roadway and new elevated roadway erected with a double-T-type main frame.

[0058] Reference Numerals in Drawings

[0059]21 existing roadway

[0060]23 existing bridge roadway

[0061]25 existing north approach roadway

[0062]27 existing south approach roadway

[0063]33 existing bridge roadway limit line

[0064]35 existing north approach roadway limit line

[0065]37 existing south approach roadway limit line

[0066]39 local roadway

[0067]40A initial portion of new elevated roadway

[0068]40B, 40C extended portion of new elevated roadway

[0069]41 new elevated roadway

[0070]41A, 41B alternative new elevated roadway

[0071]43 ramp unit

[0072]45 moveable ramp unit

[0073]47A, 47B, 47C, 47F, 47G bridging unit with portal-type main frame

[0074]47L, 47M, 47N bridging unit with double-T-type main frame

[0075]48A, 48B additional bridging unit

[0076]49 additional ramp unit

[0077]50 existing load-carrying structural member

[0078]51 portal-type main frame

[0079]53 double-T-type main frame

[0080]55 T-type main frame

[0081]57 base assembly

[0082]58 elevated assembly

[0083]59 splice assembly

[0084]60 new elevated roadway construction work area (prior art)

[0085]61 bridge roadway restoration area (prior art) 63A, 63B bridge roadway restoration area 65 construction equipment 66 contractor's field office 67 restoration equipment

DETAILED DESCRIPTION

[0086] Description and Operation of Preferred Embodiment

[0087] In the first example, FIG. 1 (PRIOR ART) shows a perspective view of an existing roadway 21 running north-south. Roadway 21, which is governed by a transportation authority, includes an existing bridge roadway 23, limited by existing bridge roadway limit lines 33. Roadway 21 also includes an existing north approach roadway 25, limited by an existing north approach roadway limit line 35, and an existing south approach roadway 27, limited by an existing south approach roadway limit line 37. Travel lane marking lines delineate existing northbound travel lanes and existing southbound travel lanes. The northbound and southbound travel lanes are separated at a median and limited on sides by roadway traffic barriers.

[0088] Existing traffic on roadway 21 fluctuates between periods of peak traffic, from early morning to late afternoon, and periods of off-peak traffic, during night hours. While average daily traffic requires four travel lanes in each direction, peak traffic requires six travel lanes in each direction, and off-peak traffic requires two travel lanes in each direction. Approach roadways 25 and 27 have been widened to satisfy peak traffic, that is they provide six northbound travel lanes and six southbound travel lanes. However, widening of bridge roadway 23 could not be implemented due to environmental restrictions, so that it provides only four northbound travel lanes and four southbound travel lanes, creating a condition commonly known as a bottleneck during periods of peak traffic. In addition to this deficiency in traffic capacity, bridge roadway 23 also requires restoration of its structural integrity.

[0089] Since, as mentioned above, widening of bridge roadway 23 could not be implemented, a conceivable solution to remedy insufficient traffic capacity of bridge roadway 23 during periods of peak traffic is to erect a new elevated roadway that will provide two elevated travel lanes in each direction. The start-up of such erecting using prior art methods is shown in FIG. 1 (PRIOR ART). It can be seen that a new elevated roadway construction work area 60 and construction equipment 65, protected by construction traffic barriers, are severely disrupting existing traffic on bridge roadway 23 by leaving only two travel lanes in each direction open to existing traffic. As erection will progress north using prior art methods, traffic disruption will continue for the duration of erecting the new elevated roadway.

[0090] It can also be seen in FIG. 1 (PRIOR ART) near the northern end of bridge roadway 23, that restoration of bridge roadway 23 is being implemented using prior art methods, preceding erection of the new elevated roadway. It is evident that a bridge roadway restoration area 61 and restoration equipment 67, protected by construction traffic barriers, are severely disrupting existing traffic by leaving only two travel lanes open to northbound traffic on bridge roadway 23. In order for this restoration to be of minimal disruption to existing traffic, the work must be performed and completed overnight, and restoration equipment 67 and the construction traffic barriers have to be removed from bridge roadway 23 before the next day's period of peak traffic. The restoration work, therefore, will be performed in an intermittent way, overnight, in sub-standard working conditions, and at a higher cost, longer duration, and lower quality, than if the roadway restoration methods of the present invention were used.

[0091] The following text and drawings provide a detailed description of the novel method of erecting a new elevated roadway 41 (see FIG. 5B) above existing roadway 21 and of the novel method of restoring structural integrity of bridge roadway 23, both with minimal disruption of existing traffic.

[0092] The new elevated roadway will be erected of a plurality of interconnected entrance/exit ramp units and bridging units. For clarity of presenting the method of erecting the new elevated roadway, ramp units and bridging units are shown in the drawings as undivided units. Actually, they will most likely be erected from individual structural members such as frames, beams, deck panels, or from pre-assembled sub-units. However, regardless of the actual pattern of erecting the new elevated roadway, the terms ramp units and bridging units will be utilized in describing the novel method.

[0093] According to standard practice, erecting procedures include but are not limited to directing and maintaining existing traffic, bringing in all necessary construction equipment and safety devices, surveying and making necessary adjustments to the existing roadway, installing, connecting and disconnecting ramp units and bridging units to each other and to the existing roadway, and removing construction equipment and safety devices from roadways prior to opening them to existing traffic.

[0094]FIGS. 2A and 2B show perspective views of the same existing roadway 21 during an initial step of erecting the new elevated roadway according to the method of the present invention. This initial step comprising erection of two entrance/exit ramp units, one of which must be moveable.

[0095] The moveable ramp unit will most likely comprise several sub-units, which will be joined together by fixed or flexible connections. The movable ramp unit may be required to be flexible longitudinally, transversely, and vertically in order to provide for an existing roadway's horizontal and vertical curve alignments and varying cross-slopes. The sub-units may be supported by rollers, sliders, pneumatic wheels, or other means, may be mounted on trailer-type platforms, or may run on a light rail-type system. The moveable ramp unit may be self-propelling, or it may be propelled along the existing roadway by an outside source, like a tractor or a cable-winch system. The moveable ramp unit may be moved as a single unit or the sub-units can be moved in sequential order, thereby reducing power requirements.

[0096] The underside of the moveable ramp unit can be used to stage construction work, store construction means, such as construction equipment and traffic barriers, and house a contractor's field office. This greatly minimizes the need to repeatedly bring construction means and workers to and from the actual construction area, thus reducing nonproductive work, time loss, and disruption of existing traffic.

[0097] The erection, as seen in FIG. 2A, involves closing four center travel lanes (two leftmost lanes in each direction) on approach roadway 27 to existing traffic by using construction traffic barriers, bringing in construction equipment 65, and erecting a ramp unit 43.

[0098] As shown in FIG. 2B, a moveable ramp unit 45 is erected next to ramp unit 43 so that an uppermost end of ramp unit 45 faces an uppermost end of ramp unit 43. It can be seen that erecting ramp units 43 and 45 has been completed, the construction traffic barriers have been removed from approach roadway 27, and an initial portion of new elevated roadway 40A, providing two new elevated northbound travel lanes and two new elevated southbound travel lanes, is open to existing traffic, as specified by the governing transportation authority.

[0099] During the erection of ramp units 43 and 45, as seen in FIGS. 2A and 2B, at least four travel lanes in each direction remained open to existing traffic on approach roadway 27 and bridge roadway 23. And since bridge roadway 23 provided four travel lanes in each direction prior to the beginning of erecting the new elevated roadway, ramp units 43 and 45 have been erected with minimal disruption of existing traffic.

[0100]FIGS. 3A and 3B show perspective views of existing roadway 21 during a subsequent step of erecting the new elevated roadway, which is erecting a bridging unit 47A. As shown in FIG. 3A, this erecting involves closing the previously erected initial portion of the new elevated roadway to existing traffic, as specified by the transportation authority, and creating a gap between ramp unit 43 and ramp unit 45 by moving ramp unit 45 northbound along existing roadway 21. Then, construction equipment 65 is brought in, and bridging unit 47A is erected.

[0101] As seen in FIG. 3B, construction equipment 65 has been stored under the newly erected bridging unit 47A, ramp unit 45 has been moved back along existing roadway 21 to adjoin bridging unit 47A, construction traffic barriers have been removed from existing roadway 21, and an extended portion of new elevated roadway 40B is open to peak traffic, as specified by the transportation authority.

[0102] As shown in FIG. 3A, two travel lanes in each direction are open to exiting traffic on bridge roadway 23 during erection of bridging unit 47A. And, since off-peak traffic requires only two travel lanes in each direction, bridging unit 47A is erected with minimal disruption of existing traffic. As seen in FIG. 3B, two new elevated travel lanes in each direction are open to existing traffic in addition to the two existing travel lanes in each direction on bridge roadway 23, therefore, four travel lanes in each direction are available to existing traffic. This is equal to the traffic capacity of bridge roadway 23 (four travel lanes in each direction) prior to the beginning of erecting the new elevated roadway, therefore, disruption of existing traffic during this step of erecting is minimal.

[0103]FIGS. 4A and 4B show perspective views of existing roadway 21 during an intermediate step of erecting the new elevated roadway, which is erecting a bridging unit 47C. As shown in FIG. 4A, this erecting involves closing a previously erected portion of the new elevated roadway to existing traffic, as specified by the transportation authority, and creating a gap between a bridging unit 47B and ramp unit 45 by moving ramp unit 45 northbound along existing roadway 21. Then, construction equipment 65 is brought in, and bridging unit 47C is erected.

[0104] As seen in FIG. 4B, construction equipment 65 has been stored under the newly erected bridging unit 47C, ramp unit 45 has been moved back along existing roadway 21 to adjoin bridging unit 47C, construction traffic barriers have been removed from existing roadway 21, and an extended portion of new elevated roadway 40C is open to peak traffic, as specified by the transportation authority.

[0105] As shown in FIG. 4A, two travel lanes in each direction are open to existing traffic on bridge roadway 23 during erection of bridging unit 47C. And, since off-peak traffic requires only two travel lanes in each direction, bridging unit 47C is erected with minimal disruption of existing traffic.

[0106] As seen in FIG. 4B, two new elevated travel lanes in each direction are open to existing traffic in addition to the two existing travel lanes in each direction on bridge roadway 23, therefore, four travel lanes in each direction are available to existing traffic. This is equal to the traffic capacity of bridge roadway 23 (four travel lanes in each direction) prior to the beginning of erecting the new elevated roadway, therefore, traffic disruption during this step of erecting is minimal.

[0107] Subsequent bridging units are erected in the same manner as described above for bridging unit 47C.

[0108]FIGS. 5A and 5B show perspective views of roadway 21 during the final step of erecting the new elevated roadway, which is erecting a bridging unit 47G. As shown in FIG. 5A, this erecting involves closing a previously erected portion of the new elevated roadway to existing traffic, as specified by the transportation authority, and creating a gap between a bridging unit 47F and ramp unit 45 by moving ramp unit 45 northbound along existing roadway 21. Then, construction equipment 65 is brought in, and bridging unit 47G is erected.

[0109] As seen in FIG. 5B, the construction equipment has been removed from existing roadway 21, ramp unit 45 has been moved back along roadway 21 to adjoin bridging unit 47G and has been fixed to existing roadway 21, construction traffic barriers have been removed from existing roadway 21, and elevated roadway 41 is open to peak traffic, as specified by the transportation authority.

[0110] As shown in FIG. 5A, two travel lanes in each direction are open to existing traffic on bridge roadway 23 during erection of the bridging unit 47G. And, since off-peak traffic requires only two travel lanes in each direction, bridging unit 47G is erected with minimal disruption of existing traffic.

[0111] As seen in FIG. 5B, two new elevated travel lanes in each direction are open to existing traffic in addition to two existing travel lanes in each direction on bridge roadway 23, therefore four travel lanes in each direction are available to existing traffic. This is equal to the traffic capacity of bridge roadway 23 (four travel lanes in each direction) prior to the beginning of erecting the new elevated roadway, therefore disruption of existing traffic during this step of erecting, as well as during erection of the entire new elevated roadway, is minimal.

[0112]FIGS. 6A and 7A show perspective views of existing roadway 21 and elevated roadway 41 during two consecutive steps of restoring structural integrity of bridge roadway 23, respectively. FIGS. 6B and 7B show cross-sectional views (looking North) of bridge roadway 23 and elevated roadway 41 during the same two steps of restoring, respectively.

[0113] First, as shown in FIG. 6A and 6B, a bridge roadway restoration area 63A within the limits of four existing center travel lanes (two leftmost lanes in each direction) is being restored. The restoration is performed by keeping the four center travel lanes closed to existing traffic (note that the traffic pattern shown in FIG. 5B has not been changed), bringing in restoration equipment 67, and restoring structural integrity of bridge roadway 23 within the limits of restoration area 63A continuously, without interruptions.

[0114] While restoring bridge roadway 23 within the limits of restoration area 63A, two outer travel lanes in each direction of bridge roadway 23 are continuously open to existing traffic in addition to two elevated travel lanes in each direction of elevated roadway 41, providing a total of four travel lanes in each direction that are continuously open to existing traffic. Since a total of four travel lanes in each direction were available to existing traffic on bridge roadway 23 prior to erecting elevated roadway 41, the restoration of bridge roadway 23 within the limits of restoration area 63A is performed with minimal disruption of existing traffic.

[0115] Then, as shown in FIG. 7A and 7B, a bridge roadway restoration area 63B within the limits of four existing outer travel lanes (two rightmost lanes in each direction) is being restored. The restoration is performed by closing the four outer travel lanes to existing traffic while rerouting existing traffic onto previously restored center travel lanes (note that the traffic pattern for elevated roadway 41 has not been changed), bringing in restoration equipment 67, and restoring structural integrity of bridge roadway 23 within the limits of restoration area 63B continuously, without interruptions.

[0116] While restoring bridge roadway 23 within the limits of restoration area 63B, two center travel lanes in each direction of bridge roadway 23 are continuously open to existing traffic in addition to two elevated travel lanes in each direction of elevated roadway 41, providing a total of four travel lanes in each direction that are continuously open to existing traffic. Since a total of four travel lanes in each direction were available to existing traffic on bridge roadway 23 prior to erection of elevated roadway 41, the restoration of bridge roadway 23 within the limits of restoration area 63B is performed with minimal disruption of existing traffic.

[0117] Thereby, the entire restoration of structural integrity of bridge roadway 23 is completed with minimal disruption of existing traffic. And, since restoration work is performed continuously, during periods of peak and off-peak traffic, the restoration is completed in a fraction of time that prior art methods would require.

[0118]FIG. 8A shows a perspective view of existing roadway 21 after erection of elevated roadway 41 and restoration of structural integrity of bridge roadway 23 have been completed with minimal disruption of traffic. All eight travel lanes (four lanes in each direction) of the entirely restored bridge roadway 23 as well as all four travel lanes (two lanes in each direction) of elevated roadway 41 are open to existing traffic, providing a total of six travel lanes in each direction. Thus, the traffic deficiency of bridge roadway 23 has been remedied and the pre-existing bottleneck condition has been eliminated by the addition of elevated roadway 41, erected with minimal disruption of traffic. Also, structural integrity of bridge roadway 23 has been restored with minimal disruption of traffic.

[0119]FIG. 8B shows a cross-sectional view (looking North) of bridge roadway 23 and elevated roadway 41 for the same traffic pattern as shown in FIG. 8A. It can be seen that a portal-type main frame 51 of elevated roadway 41 is supported by an existing load-carrying structural member 50 of bridge roadway 23. This type of main frame is shown in all previous drawings, however, other types of main frames may be used in conjunction with the novel method of the present invention.

[0120]FIG. 8C shows a cross-sectional view of bridge roadway 23 and an alternative new elevated roadway 41A, erected with a double-T-type main frame 53, supported by load-carrying member 50 of bridge roadway 23.

[0121]FIG. 8D shows a cross-sectional view of bridge roadway 23 and an alternative new elevated roadway 41 B, erected with a T-type main frame 55, supported by load-carrying member 50 of bridge roadway 23.

[0122] Description and Operation of Additional Embodiments

[0123] The next example assumes that two additional travel lanes in the northbound direction are required to be built along the same existing roadway 21 in order to provide a connector for a local road 39. This requirement may be satisfied by erecting an additional two-lane elevated roadway above the two rightmost northbound travel lanes of bridge roadway 23 and alongside the previously erected elevated roadway 41 using the preferred method of the present invention. However, an alternative method of erecting a new elevated roadway with minimal disruption of traffic will be utilized for erecting the additional elevated roadway.

[0124] According to this alternative method, a new elevated roadway is erected above an existing roadway in multiple steps of a plurality of ramp units and bridging units. Entrance/exit ramp units may be erected at predetermined locations at such a time that disruption of existing traffic will be minimal. Each step of erecting a bridging unit comprises closing a predetermined number of existing travel lanes to existing traffic during a period of off-peak traffic, erecting at least one bridging unit over the closed existing travel lanes, and opening the previously closed travel lanes, beneath the erected portion of the new elevated roadway, to existing traffic to meet peak traffic demand.

[0125] This additional method is further described in the following text and the following FIGS. 9A and 9B, which show perspective views of existing roadway 21, elevated roadway 41, and local road 39 during two consecutive sub-steps, respectively, of erecting a bridging unit 47B of the additional elevated roadway with minimal disruption of traffic.

[0126]FIG. 9A shows that an additional ramp unit 49 and an additional bridging unit 48A have been previously erected and have been used to set up construction equipment 65, and to deliver other construction means and construction materials to the work area. It can also be seen in FIG. 9A, that during a period of off-peak traffic, as specified by the transportation authority, the two rightmost northbound travel lanes of bridge roadway 23 are closed to existing traffic using construction traffic barriers, while existing traffic is diverted onto the remaining northbound travel lanes. A bridging unit 48B is then erected with minimal disruption of traffic using construction equipment 65.

[0127] Then, as can be seen in FIG. 9B, construction equipment 65 and other construction means have been stored on the previously erected bridging unit 48B, construction traffic barriers have been removed from the existing roadways, and the two rightmost northbound travel lanes are open to peak traffic, as specified by the transportation authority, beneath bridging units 48A and 48B, and ramp unit 49.

[0128] The step of erecting bridging units, as shown in FIGS. 9A and 9B, is repeated until all of a predetermined number of bridging units are erected. Entrance/exit ramp units are erected at predetermined locations at such a time that disruption of existing traffic will be minimal, and the fully erected additional elevated roadway (not shown) is opened to existing traffic, as specified by the transportation authority.

[0129] Thus, by utilizing this alternative method, the new elevated roadway is erected with minimal disruption of existing traffic, because at each step, the existing roadway is open to existing traffic during periods of peak traffic, and the predetermined number of existing travel lanes is closed to existing traffic only during periods of off-peak traffic.

[0130] In the previous examples, ramp units and bridging units were shown to be erected as undivided units. Actually, however, ramp units and bridging units are erected from individual structural members such as main frames, beams, braces, and deck panels. A novel structural form of a main frame further amplifies the advantages of the novel method of erecting new elevated roadways with minimal disruption of existing traffic.

[0131] According to this novel form, the main frame comprises at least one base assembly, which is supported beneath a surface of an existing roadway, at least one elevated assembly, which is supported by the base assembly, and at least one splice assembly, which connects the elevated assembly to the base assembly and which is located above the surface of the existing roadway.

[0132] The next example provides a detailed procedure for erecting a main frame of a bridging unit of a new elevated roadway. Although the main frame utilized in this example is a double-T-type, this procedure applies equally to other types of main frames.

[0133]FIGS. 10A, 10B and 10C show detailed perspective views of the same existing bridge roadway 23 and an alternative new elevated roadway 41A, during three consecutive sub-steps, respectively, of erecting a bridging unit 47N. (The completely erected bridging unit 47N is shown only in FIG. 10C). FIG. 10D shows a cross-sectional view of bridge roadway 23 and elevated roadway 41A, with a double-T-type main frame 56.

[0134] It can be seen in FIG. 10A that erection of bridging unit 47N begins during a period of peak traffic with erecting base assemblies 57, while existing traffic is using elevated roadway 41A, above the work area. Also seen in FIG. 10A is a previously erected portion of elevated roadway 41 A, which includes a bridging unit 47M and a movable ramp unit 45, construction equipment 65, which is stored under elevated roadway 41A, and a contractor's field office 66, which is built into the underside of ramp unit 45.

[0135] Erecting base assemblies 57 includes bringing in all necessary construction equipment and safety devices, surveying and making necessary adjustments to an existing load-carrying structural member 50 (not shown), located beneath the surface of bridge roadway 23, installing base assemblies 57 and connecting them to the existing load-carrying members. Since the erecting is conducted under ramp unit 45, the work is performed during day time, with minimal time pressure and with minimal disruption of peak traffic on bridge roadway 23 and on elevated roadway 41A.

[0136]FIG. 10B shows a progression of erecting bridging unit 47N, which is performed between the previously erected bridging unit 47M and ramp unit 45 during a period of off-peak traffic. The erection involves closing the previously erected portion of elevated roadway 41A to existing traffic, as specified by the transportation authority, creating a gap in the previously erected portion of elevated roadway 41A by moving ramp unit 45 along bridge roadway 23. Then, construction equipment 65 is set up and elevated assemblies 58 are installed atop of the previously installed base assemblies 57.

[0137]FIG. 10C shows that elevated assemblies 58 have been connected to base assemblies 57 by splice assemblies 59, construction equipment 65 has been stored under elevated roadway 41A, ramp unit 45 has been moved back along roadway 23 to adjoin bridging unit 47N, construction barriers have been removed from bridge roadway 23, and an extended portion of elevated roadway 41A is open to peak traffic, as specified by the transportation authority.

[0138] It can also be seen in FIG. 10C, that base assemblies 57 are erected under ramp unit 45 for the next bridging unit, while existing traffic is using elevated roadway 41A, above the work area. The work is again performed during daytime with minimal time pressure and with minimal disruption of peak traffic on bridge roadway 23 and elevated roadway 41 A.

[0139]FIG. 10D shows a cross-sectional view of FIG. 10C, where main frame 56 is erected of base assemblies 57, which are supported by load-carrying member 50 beneath the surface of bridge roadway 23, and elevated assembly 58, which are spliced by splice assemblies 59 above the surface of bridge roadway 23. It can also be seen in FIG. 1 OD that two travel lanes in each direction of elevated roadway 41A, in addition to two travel lanes in each direction of bridge roadway 23, are open to meet peak traffic demand.

[0140] In order to further expedite erecting main frames 56, assemblies 57, 58, and 59 are pre-matched during fabrication. Thereby, erection of main frames 56 is performed in minimal time, with minimal disruption of traffic, and results in better quality, higher reliability, and increased productivity than if erecting were performed solely during periods of off-peak traffic.

[0141] Conclusion, Ramifications, and Scope of Invention

[0142] Thus, the reader will see that erecting a new elevated roadway above an existing roadway and restoring structural integrity of the existing roadway may be performed with minimal disruption of traffic using the methods and devices of the present invention.

[0143] While the description above contains many specificities, these should not be construed as limitations on the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention.

[0144] Many other variations are possible, for example:

[0145] The methods and devices of the present invention are applicable to a great variety of different types of existing roadways carrying any number of existing travel lanes, and to elevated roadways carrying as many elevated travel lanes as required by traffic demand.

[0146] Erection of a new elevated roadway may originate in the middle of an existing roadway and erection may progress in two opposite directions simultaneously by utilizing two moveable ramp units. Thus, erection time may be cut in half. In order to minimize impact on traffic, a portion of the existing roadway, where the ramp units are initially erected, may be temporarily widened or the ramp units may be assembled off-site and erected on-site during a period of off-peak traffic.

[0147] Depending on traffic demand during erection of new elevated roadway, the moveable ramp unit may provide a lesser number of travel lanes than the bridging units, thus reducing power requirements. In its final location, the moveable ramp unit may be replaced with a fixed entrance/exit ramp unit, that provides at least as many travel lanes as provided by the bridging units. Or, the moveable ramp unit may be fixed at its final location, and additional ramp units may be erected.

[0148] Since the width of travel lanes is standard, a moveable ramp unit can be assembled and disassembled from standard sub-units of easily transportable size. This modular ramp unit can be transported to and be utilized on many different construction projects.

[0149] Ramp units may be split at the ends in order to provide direct access for fast-moving traffic and emergency vehicles to the leftmost travel lanes of an existing roadway that run beneath a new elevated roadway.

[0150] The new elevated roadway may be designated for “passenger cars only”, thus providing a natural separation of car traffic and truck traffic. Traffic separation means, such as appropriate traffic signs, attenuating barriers, and traffic gates with overhead clearance tracking devices, shall be installed on the existing roadway's approaches to the new elevated roadway. Such an elevated roadway may be used for alternating direction of traffic during peak hours to coincide with commuter needs.

[0151] Different types of main frames may be utilized to accommodate various traffic patterns, such as different percentage of trucks in an overall traffic, special use travel lanes, or incorporation of a light rail line.

[0152] Accordingly, the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given. 

What is claimed is:
 1. A method of erecting a new elevated roadway of a predetermined length disposed above an existing roadway, said existing roadway, which is governed by a transportation authority, providing a plurality of existing travel lanes carrying existing traffic of a varying volume, said new elevated roadway providing a plurality of elevated travel lanes comprises a predetermined number of ramp units and a predetermined number of bridging units, each of said bridging units having a roadway deck oriented mostly parallel to said existing roadway, each of said ramp units having a mostly inclined roadway deck, said method comprising the steps of: (a) closing a predetermined number of said existing travel lanes to said existing traffic as specified by said transportation authority, erecting at least two of said ramp units, at least one of which shall be a movable ramp unit, at a predetermined location over the closed travel lanes so that an uppermost end of said movable ramp unit faces an uppermost end of another of said ramp units, and (b) repeatedly, until said predetermined number of said bridging units is erected, closing a previously erected portion of said new elevated roadway to said existing traffic as specified by said transportation authority, creating a gap in said previously erected portion of said new elevated roadway by moving said movable ramp unit along said existing roadway, erecting at least one of said bridging units in said gap, and opening an extended portion of said new elevated roadway to said existing traffic as specified by said transportation authority, whereby said new elevated roadway will be erected above said existing roadway with minimal disruption of said existing traffic.
 2. The method in accordance with claim 1, further including a step of widening a predetermined portion of said existing roadway by constructing additional travel lanes.
 3. The method in accordance with claim 1, further including a step of erecting a traffic separation means on said existing roadway, whereby precluding truck traffic access to a predetermined number of travel lanes designated as passenger cars only travel lanes by said transportation authority.
 4. The method in accordance with claim 1, further including the step of replacing said moveable ramp unit with a fixed ramp unit at a predetermined location.
 5. The method in accordance with claim 1, further including the step of storing construction means underneath said previously erected portion of said new elevated roadway.
 6. A method of restoring a structural integrity of a predetermined portion of an existing roadway, said existing roadway, which is governed by a transportation authority, providing a plurality of existing travel lanes carrying existing traffic of a varying volume, said method comprising the steps of: (A) first erecting a new elevated roadway of a predetermined length disposed above said existing roadway, said new elevated roadway providing a plurality of elevated travel lanes comprises a predetermined number of ramp units and a predetermined number of bridging units, each of said bridging units having a roadway deck oriented mostly parallel to said existing roadway, each of said ramp units having a mostly inclined roadway deck, said erecting comprising: (a) closing a predetermined number of said existing travel lanes to said existing traffic as specified by said transportation authority, erecting at least two of said ramp units, at least one of which shall be a movable ramp unit, at a predetermined location over the closed travel lanes so that an uppermost end of said movable ramp unit faces an uppermost end of another of said ramp units, and (b) repeatedly, until said predetermined number of said bridging units is erected, closing a previously erected portion of said new elevated roadway to said existing traffic as specified by said transportation authority, creating a gap in said previously erected portion of said new elevated roadway by moving said movable ramp unit along said existing roadway, erecting at least one of said bridging units in said gap, and opening an extended portion of said new elevated roadway to said existing traffic as specified by said transportation authority; (B) then restoring said structural integrity of said predetermined portion of said existing roadway as specified by said transportation authority by: repeatedly, until said structural integrity of said predetermined portion of said existing roadway is restored, closing a predetermined number of said existing travel lanes to said existing traffic while rerouting said existing traffic onto said elevated travel lanes of said new elevated roadway, restoring structural integrity of said predetermined portion of said existing roadway within the limits of said predetermined number of said existing travel lanes closed to said existing traffic, and opening the restored existing travel lanes to said existing traffic, whereby said structural integrity of said predetermined portion of said existing roadway will be restored with minimal disruption of said existing traffic.
 7. The method in accordance with claim 6, further including a step of widening a predetermined portion of said existing roadway by constructing additional travel lanes.
 8. The method in accordance with claim 6, further including a step of erecting a traffic separation means on said existing roadway, whereby precluding truck traffic access to a predetermined number of travel lanes designated as passenger cars only travel lanes by said transportation authority.
 9. The method in accordance with claim 6, wherein said restoring of said structural integrity of a predetermined portion of said existing roadway located below said new elevated roadway is performed concurrently with erecting said new elevated roadway.
 10. The method in accordance with claim 6, further including the step of replacing said moveable ramp unit with a fixed ramp unit at a predetermined location.
 11. The method in accordance with claim 6, further including the step of storing construction means underneath said previously erected portion of said new elevated roadway.
 12. A method of erecting a new elevated roadway of a predetermined length disposed above an existing roadway, said existing roadway, which is governed by a transportation authority, providing a plurality of existing travel lanes carrying existing traffic of a varying volume, said new elevated roadway providing a plurality of elevated travel lanes comprises a predetermined number of ramp units and a predetermined number of bridging units, each of said bridging units having a roadway deck oriented mostly parallel to said existing roadway, each of said ramp units having a mostly inclined roadway deck, said method comprising the steps of: (a) repeatedly, until said predetermined number of said ramp units is erected, closing a predetermined number of said existing travel lanes to said existing traffic as specified by said transportation authority, erecting at least one of said ramp units of said new elevated roadway over the closed travel lanes at a predetermined location and in a predetermined orientation, (b) repeatedly, until said predetermined number of said bridging units is erected, closing a predetermined number of said existing travel lanes to said existing traffic as specified by said transportation authority, erecting at least one of said bridging units at a predetermined location over the closed travel lanes, and opening the closed travel lanes to said existing traffic as specified by said transportation authority, (c) opening said new elevated roadway to said existing traffic as specified by said transportation authority, whereby said new elevated roadway will be erected above said existing roadway with minimal disruption of said existing traffic.
 13. The method in accordance with claim 12, further including a step of widening a predetermined portion of said existing roadway by constructing additional travel lanes.
 14. The method in accordance with claim 12, further including a step of erecting a traffic separation means on said existing roadway, whereby precluding truck traffic access to a predetermined number of travel lanes designated as passenger cars only travel lanes by said transportation authority.
 15. The method in accordance with claim 12, further including the step of storing construction means on the previously erected bridging units.
 16. A method of restoring a structural integrity of a predetermined portion of an existing roadway, said existing roadway, which is governed by a transportation authority, providing a plurality of existing travel lanes carrying existing traffic of a varying volume, said method comprising the steps of: (A) first erecting a new elevated roadway of a predetermined length disposed above said existing roadway, said new elevated roadway providing a plurality of elevated travel lanes comprises a predetermined number of ramp units and a predetermined number of bridging units, each of said bridging units having a roadway deck oriented mostly parallel to said existing roadway, each of said ramp units having a mostly inclined roadway deck, said erecting comprising: (a) repeatedly, until said predetermined number of said ramp units is erected, closing a predetermined number of said existing travel lanes to said existing traffic as specified by said transportation authority, erecting at least one of said ramp units of said new elevated roadway over the closed travel lanes at a predetermined location and in a predetermined orientation, (b) repeatedly, until said predetermined number of said bridging units is erected, closing a predetermined number of said existing travel lanes to said existing traffic as specified by said transportation authority, erecting at least one of said bridging units at a predetermined location over the closed travel lanes, and opening the closed travel lanes to said existing traffic as specified by said transportation authority, (c) opening said new elevated roadway to said existing traffic as specified by said transportation authority; (B) then restoring said structural integrity of said predetermined portion of said existing roadway as specified by said transportation authority by: repeatedly, until said structural integrity of said predetermined portion of said existing roadway is restored, closing a predetermined number of said existing travel lanes to said existing traffic while rerouting said existing traffic onto said elevated travel lanes of said new elevated roadway, restoring structural integrity of said predetermined portion of said existing roadway within the limits of said predetermined number of said existing travel lanes closed to said existing traffic, and opening the restored existing travel lanes to said existing traffic, whereby said structural integrity of said existing roadway will be restored with minimal disruption of said existing traffic.
 17. The method in accordance with claim 16, further including a step of widening a predetermined portion of said existing roadway by constructing additional travel lanes.
 18. The method in accordance with claim 16, further including a step of erecting a traffic separation means on said existing roadway, whereby precluding truck traffic access to a predetermined number of travel lanes designated as passenger cars only travel lanes by said transportation authority.
 19. The method in accordance with claim 16, further including the step of storing construction means on the previously erected bridging units.
 20. A main frame of a new elevated roadway, said new elevated roadway is disposed above an existing roadway, said main frame comprising: (a) at least one base assembly, a lower end of the base assembly is supported below a surface of said existing roadway, an upper end of the base assembly is located above said surface of said existing roadway, (b) at least one elevated assembly, a lower end of the elevated assembly is supported by said upper end of the base assembly, and (c) at least one splice assembly connecting the elevated assembly to the base assembly above said surface of said existing roadway. 